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Mike Bullivant's diary: Part two

Updated Thursday, 27th September 2007

Mike Bullivant's diary of a castaway, from the BBC/OU series Rough Science 1

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Mike filters water Copyrighted  image Icon Copyright: Production team

Tuesday 21st September - Day 1

After our success in the first Rough Science programme, it’s on to the second in the series. What devilish challenges will Kate (Humble) be setting us this time? After the usual bumpy 45-minute hike up to our prison laboratory in 4-wheel drives early on the first day of filming Programme 2, we all meet to be given our tasks for the next three days. My challenge is to produce some photosensitive film to use in a castaway camera that Jonathan’s been asked to build.

Yai, yai, yai, I thought things were going too well!!!! Where do we start with this one? It’s not going to be as easy as extracting rosemary oil, I can tell you!! That was a doddle compared to this. Now, I know that silver halide salts (especially silver chloride and iodide) are photosensitive, as they were used by the pioneers of photography back in the 19th century, but where on earth (or more precisely, where on Capraia) do we find the raw materials for these compounds?

Vanessa, a marine biologist, tells me that seaweed, which is to be found all round the island’s coastline, is a good source of iodine, so we could think about making silver iodide. But where could we get the silver from, and how do we react the iodine and silver together to give silver iodide? Luckily, someone notices that Vanessa’s wearing a silver bracelet, and she’s ‘persuaded’ to donate it to the cause. She has no choice, frankly. Our next step is to harvest some seaweed and try to extract the iodine from it. So, it’s off to the beach for Vanessa and me.

It turns out to be one of the most pleasant afternoons I’m going to spend on the island. V’s great fun to be with. She knows her stuff, and we have a great time as we clamber down the mountainside on our hunter-gathering trip.

We make it gingerly down the cliff face to the shoreline, and before long, our castaway mermaid is in her bikini and up to her neck in the Mediterranean. We gather as much as we think we’ll need of a particular seaweed that V assures me will do the trick.

We also have to collect some seawater to use in a castaway, seawater-battery (see later). Shame that the bucket we’d humped all the way down to the sea is found to have a hole in its bottom! Could this be an act of sabotage on the part of the production crew, or is paranoia setting in?

When we return to our prison laboratory, V and I set about burning the seaweed in a wok that we’d found in the prison grounds earlier in the day; what a weird thing to find in a prison complex! Dissolving the ashes from the incinerated seaweed in water, and carefully filtering off the undissolved solid matter and reducing the solution down, leaves us with a clear liquid that we think (hope!) will be a fairly concentrated solution of sodium and/or potassium iodides.

Now all we have to do is to get the iodide ions in this solution to react with the silver atoms in Vanessa’s bracelet. It won’t happen spontaneously just by mixing the two together. To get them to react, we have to construct an electrolytic cell, powered by a collection of ten seawater batteries all wired up in series.

In this way, we hope to produce enough current to drive the electrolytic cell, one electrode of which will be the bracelet.

For the cell’s other electrode, we use the graphite (lead) from a pencil. The theory’s sound, but will it work? The only way to find out is to connect our ‘graphite/silver’ electrolytic cell up to the seawater power plant, and see what happens.

After passing current through the cell for an hour or so, it’s clear that something’s going on, but what, and will the product be the one we want, silver iodide? We decide to leave the experiment set up with current flowing through the cell overnight ...

On the drive down the mountain at the end of Day 1, it’s clear that Anna and Mike have not exactly hit it off together today. They’ve been off round the island collecting plants from which they hope to extract the dyes to make a Rough Science flag. It sounds as if Mike would much rather be doing something else, and he’s not at all confident that the extracted dyes will be anything other than ‘yucky brown’. Time will tell. Anna battles on despite Mike’s pessimism. Good for her! Others’ lack of enthusiasm is always a heavy burden, no matter what the circumstances.

Wednesday 22nd September - Day 2

The first, rather bizarre instruction that we’re all given by Kate on arrival at the prison is to pee into a bucket every time we feel the need to go to the loo. Apparently, Anna and Mike L need urine to act as one of the mordants for their dyeing process. Seems a reasonable request to me, but I must remember to do it, rather than popping round the back of the prison every time I get the urge.

Kate, Vanessa and I can’t wait to see if we’ve managed to produce any silver iodide in our electrolytic cell. It should be easy enough to tell, as the compound’s bright yellow. We uncover the graphit/silver cell with some trepidation (we’d purposely kept the cell covered and in the dark so as to protect from sunlight any silver iodide that may have formed). As we reveal the solution in the cell (the electrolyte), we can see that a yellow solid has indeed formed.

Yippee!! The silver electrode, as all of us but Vanessa had hoped, has been eaten away overnight as its silver atoms have converted into silver ions under the influence of the current from the line-up of seawater batteries. We feel justifiably pleased with ourselves, but as with most of the Rough Science challenges, it’s been only a partial success. It appears that Vanessa’s bracelet wasn’t actually pure silver.

Judging from the greenish colour of some of the solid deposits in the electrolytic cell, the bracelet had also contained some copper, and we’ve managed to produce some copper salts as well as the yellow silver iodide that we desperately need for our photographic film. But never mind, at least we’ve managed to produce some silver iodide. Much of it has settled out as a solid at the bottom of the cell, but there’s also likely to be some suspended in solution.

All we have to do now is test whether a piece of white paper soaked in some of the silver iodide solution from the cell is photosensitive. We decide to place a key over the wet paper and leave it in the sun to see what happens. If all goes to plan, the parts of the paper exposed to sunlight will darken as the silver iodide is converted back to silver under the action of the sun’s rays. The parts of the paper that the sun’s rays can’t reach will remain white.

After an hour or so, we return to the key to see what change, if any, has taken place. Lo and behold, when we remove the key, there’s definitely a distinct, white key shape set against a brown background. But without developers, will this process be enough to create an image when a similar sheet of white paper soaked in silver iodide is used in Jonathan’s camera.

I suspect not, there’s only one way to find…but the camera’s not ready yet. Jonathan’s still working on it, and you can see why it’s taking him so long. It’s going to be a beautiful piece of kit, but will it be ready in time? We’ve only one day left to complete this particular challenge. It’s going to be touch and go.

As Jonathan beavers away at his camera, Vanessa and I spend the rest of Day 2 helping Mike L and Anna prepare the harvest of pine cones, vines and berries that they’re going to try out as dyes for the Rough Science flag.

Thursday 23rd September - Day 3

I spend much of this last day helping out with the flag challenge, trying out combinations of mordants and dyes. Anna and Mike need to know which combinations are going to produce the best colours. Trying all of them out on a small scale is the best way to find out, and this becomes my contribution to the flag-dyeing.

By late afternoon on Day 3, Jonathan’s castaway camera is finally ready for us to load with home-made film. Unfortunately, we only have an hour or so of daylight left in which to complete the challenge, and from our experience with the key yesterday, I fear (pretty well know!) that this isn’t going to be long enough to produce an image on the film. We’ve just not had the time to develop (literally) the process.

At the end of the day, it’s time to see how successful we’ve been. Have we managed to take a photograph? As I suspected, we’ve not been able to produce an image on the paper in the camera. Still, we tried, and despite the disappointment, I feel we can be quite proud of ourselves to have produced any kind of result at all (with the key yesterday). After all, we had actually managed to produce a light-sensitive compound from little more than a pile of wet seaweed and a silver bracelet, and that’s quite an achievement ... isn’t it?

Notwithstanding our failure with the camera, Mike and Anna have actually managed to produce a flag with four distinct colours to it. As the flag’s hoisted up an improvised flagpole, we can feel some kind of satisfaction from knowing that they’ve managed to exploit nature so successfully, even though the colours are a bit dull, and not the vibrant hues that Kate had asked for. The brilliant idea of using a key motif in the flag’s design was Angie’s (one of the production team). It’s a fitting symbol for our prison home, and for the ethos of the Rough Science series – unlocking the minds of the science-phobic back home.

So, Programme 2 has been a bit of a curate’s egg, in that we’ve had some qualified success. Not that this would make any difference as far as our next set of challenges was concerned. What had Kate Humble got up her sleeve for us in programme 3?! We wouldn’t find out till the after tomorrow, which is to be a rest day. Thank god, we’re going to have a day off! After the exertions and tension of the last three days, we all need it.

[Postscript: As an experiment to see what would have been possible had we been given more time, we decided to repeat the exercise with the key, but this time leaving it exposed to sunlight for much longer. It turned out that after only four hours exposure to the sun’s rays, we could produce a much more distinct image of the key on our silver iodide coated paper. Even after only this short amount of time, the silver iodide had turned a much darker brown, and the image of the key was much more pronounced and well defined. If only we’d had more time ...

On our way back to the UK at the end of the filming, we spent a day in Pisa. It was really satisfying to see that many of the city’s buildings are actually painted in the same flat, pastel colours as the dyes that Anna and Mike L had managed to create for our flag. This is no accident, surely. The paints the people of Pisa had used on their buildings were probably produced from the same local plant materials, and in much the same way, as our dyes. Comforting, in a strange sort of way.]




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